1. Field of the Invention
The field of the present invention relates to communication systems and methods and, in particular, to wireless local loop systems and methods of communicating in wireless local loop systems.
2. Background
Telephone service has traditionally been provided to business and residential customers through fixed landlines that are routed from the telephone network through switching stations to their local destinations. However, the costs associated with providing telephone services to some customers (i.e., those located in remote regions, or geographically harsh environments, or high rise buildings) using conventional cabling methods can be prohibitively expensive. For many network operators this expense is unavoidable, because the provision of service to such customers is often not optional under regulatory requirements to deliver service universally regardless of the cost, sometimes referred to as a xe2x80x9cuniversal service obligation.xe2x80x9d
In addition, conventional landlines can be expensive and time-consuming to deploy. Service to potential customers can be delayed while telephone lines and cables are being 25 deployed, causing frustration to such customers. In certain areas, the telephone provider may have to spend an excessive amount on telephone lines which might ultimately serve only a small client base. Moreover, maintenance of telephone cabling (e.g., copper lines) can be expensive, and such cabling can be subject to occasional faults which require repair or replacement and can be a significant inconvenience for customers.
The delay and expense of establishing landlines may also be a disadvantage to a telephone provider desiring to enter a new market quickly and cost effectively. Recent legislation in the United States has increased competition in local markets for provision of basic and enhanced telephone services. Telephone providers wanting to enter these markets rapidly so as to compete against or bypass an incumbent local access network operator may be at a disadvantage if required to deploy an extensive ground network of cabling in order to provide service.
Certain telephone customers have specialized needs that are difficult or unduly expensive to meet using only landlines to connect service. In particular, customers which experience high xe2x80x9cchurnxe2x80x9d (i.e., call turnover) or which require temporary provisioning may not be adequately served by existing landline connections. At the same time, it may not be cost effective to add expensive landlines where only temporary provisioning is required. Examples of customers having such specialized needs may include, e.g., universities and other educational institutions, hospitals, marinas, shopping malls, large exhibitions, construction sites, caravan parks, and the like.
As an additional consideration, a single type of telephone service may not be adequate to address the needs of disparate customers. For example, industrially undeveloped or under-developed countries or regions may require only basic telephone service (i.e., POTS service), whereas industrially advanced countries or regions may require high quality voice, data capability and custom calling features. Customers starting out with basic service may eventually want or need to upgrade to more advanced telephone features.
There is a need for a communication system allowing rapid and/or expedient rollout, so as to provide service in a timely fashion to both presently served markets as well as remotely located or otherwise hard-to-access customers. There is also a need for a communication system allowing easier and more cost-effective service for remote or rural customers. There is further a need for a telephone service that accounts for the needs of both basic and relatively advanced users, and which allows upward migration of features such as high quality voice, data and custom calling options. Additionally, there is need for a communication system that can provide economic telephone service to select customers who have specialized needs, including high churn or temporary provisioning.
The invention provides in one aspect a communication system for providing wireless local loop services which can be deployed relatively rapidly and which offers the benefits of advanced telephony features.
In one embodiment, a customer premises remote unit (CPRU) has a wireless transceiver for over-the-air communication, and is physically located at or near a customer site. The CPRU communicates wirelessly with an intelligent base station (IBS) that is preferably capable of supporting multiple access communication so as to enable support of multiple CPRUs and/or other users. The intelligent base station directly connects, without the assistance of a base station controller, to a mobile switching center (MSC), preferably through a GSM A-interface or a derivative thereof. The mobile switching center allows access to a public switched telephone network (PSTN). Telephones or other devices connected to the CPRU can thereby communicate with the PSTN over the connection established between the CPRU and the intelligent base station, through the mobile switching center. The intelligent base station preferably employs a subset of GSM functionality, enabling the CPRU to take advantage of various advanced telephony features, and offering an upward migration path for those users initially starting with basic telephone service. Because the intelligent base station can connect directly to the mobile switching center, deployment can be conducted more rapidly, without the need for connecting and configuring base station controllers in the area to be serviced.
In another embodiment, a transcoder and rate adapter unit is added between the intelligent base station and the mobile switching center. In this embodiment, the transcoding rate adaption unit and the CPRU represent peer-to-peer endpoints for ciphering.
In another aspect, an intelligent base station connected directly to a GSM mobile switching center is capable of communicating with both mobile users and fixed wireless local loop customers, by employing a flexible and robust over-the-air protocol for multiple access communication. In a preferred embodiment, the intelligent base station communicates with user stations (such as mobile handsets, or fixed CPRUs) by dividing a time frame into time slots and assigning the time slots to individual user stations, thereby carrying out time division multiple access communication. The intelligent base station preferably transmits and receives messages which have been encoded using spread spectrum techniques, and thereby transmits and receives messages over a bandwidth that is relatively wide compared with typical narrowband techniques. In one embodiment, the intelligent base station transmits over a first frequency band, while the user stations transmit over a second frequency band, thereby implementing frequency division multiple access (FDMA) and/or frequency division duplex (FDD) communication.
In another embodiment, a wireless local loop subsystem and a wireless mobile subsystem coexist in a single communication system. The wireless local loop subsystem comprises one or more intelligent base stations. The intelligent base stations are connected to a mobile switching center (MSC) over a GSM A-interface. In a particular version of such an embodiment, a intelligent base stations within a cluster are connected over physical links, and when a mobile station communicating with a first intelligent base station in the cluster is handed over to a second intelligent base station in the cluster, signalling and bearer channels supporting the call are tunneled through the first intelligent base station (which becomes the anchor base station) to the second intelligent base station (which becomes the relay base station) over a physical link. The call then proceeds with communication being carried through both the anchor and relay base stations.
Further embodiments as well as modifications, variations and enhancements of the invention are also described herein.